This invention relates to fluid translating devices and, more particularly, to rotary, vane-type pumps or motors having an improved rotor.
Rotary, vane-type pumps and motors have been employed as fluid translating devices for many years. U.S. Pat. No. 2,600,633 granted June 17, 1952 to H. French discloses a constant volume, rotary, vane-type pump, while U.S. Pat. No. 3,523,746 granted Aug. 11, 1970 discloses a variable volume, rotary, vane-type pump. Those patents are illustrative of the rotary, vane-type pumps and motors previously employed and the improved rotor of this invention is useful in the constant and variable volume devices they illustrate.
As shown in FIG. 2 of the drawing of this specification, prior art rotors 1 for rotary, vane-type pumps and motors have slots 3 therein that are substantially straight along the entire length of their side walls. The bottom of the slot may be planar, arcuate, as shown in FIG. 2, or bulbous, as disclosed in U.S. Pat. No. 2,711,698 granted June 28, 1955 to L. Bozek, et al. Each slot receives a complementary vane 5 which during the operation of the pump or motor is subjected to forces that cause it to reciprocate in the slot. While the vane is totally positioned inside the slot, its axis is substantially along the axis of the slot. However, as the outward end of the vane increasingly emerges from the slot, the vane tilts in the direction opposite the rotation of the rotor, so that it is positioned with its axis oblique to the axis of the slot and has a bottom edge in contact with a side wall of the slot.
Because the vane is made of a harder material than the rotor, continued reciprocation of the vane against the slot can wear groove 7 in the side wall of the slot intermediate its ends, as shown in FIG. 2, especially if the fluid used in the pump or motor has a low viscosity. Formation of the groove then allows the vane to tilt or tip even more obliquely to the axis of the slot as it reciprocates, thereby wearing a deeper groove which allows further tilting; ad infinitum. Initially, as the groove begins to wear in the slot, the pump or motor will become noisier and produce less fluid flow or pressure. Ultimately, the groove will allow the vane to tilt so obliquely to the axis of the slot that the vane will become wedged in the slot in a manner that prevents it from reciprocating therein and the vane will be broken by the forces exerted on it as the rotor continues to rotate in the pump or motor. Such a broken vane will then cause further damage to other portions of the pump or motor as the rotor continues to rotate.
Accordingly, it will be apparent that a wear resistant rotor slot would be advantageous and desirable, especially for rotors to be employed in pumps or motors translating low viscosity liquids.